How Hackers Broke WhatsApp With Just a Phone Call

You've heard the advice a million times. Don't click links in suspicious emails or texts. Don't download shady apps. But a new Financial Times report alleges that the notorious Israeli spy firm NSO Group developed a WhatsApp exploit that could inject malware onto targeted phones—and steal data from them—simply by calling them. The targets didn't need to pick up to be infected, and the calls often left no trace on the phone's log. But how would a hack like that even work in the first place?

WhatsApp, which offers encrypted messaging by default to its 1.5 billion users worldwide, discovered the vulnerability in early May and released a patch for it on Monday. The Facebook-owned company told the FT that it contacted a number of human rights groups about the issue and that exploitation of this vulnerability bears "all the hallmarks of a private company known to work with governments to deliver spyware." In a statement, NSO Group denied any involvement in selecting or targeting victims but not its role in the creation of the hack itself.